TUN/TAP

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In computer networking, TUN and TAP are virtual network kernel drivers — they simulate network devices using software. Whereas ordinary network devices (e.g. eth0) are directly backed by hardware network adapters, packets sent to/from TUN/TAP devices are forwarded from/to user-space programs. TUN simulates a point-to-point network device, while TAP simulates an Ethernet device. TUN works with IP packets, while TAP works with Ethernet frames.

TUN/TAP is used for:

• virtual private networks
  • OpenVPN, Ethernet/IP over TCP/UDP; encrypted, compressed
  • tinc [1], Ethernet/IPv4/IPv6 over TCP/UDP; encrypted, compressed
  • VTun [2], Ethernet/IP/serial/Unix pipe over TCP; encrypted, compressed, traffic shaping
  • OpenSSH
  • ICMPTX [3], IP over ICMP (ping)
  • NSTX [4], IP over DNS
  • HTun [5], IP over HTTP
  • coLinux, Ethernet/IP over TCP/UDP
  • Hamachi
• virtual machine networking
  • Bochs
  • coLinux
  • QEMU
  • Hercules (S/390 emulator)

TUN/TAP drivers are available on at least the following platforms:

• FreeBSD
• Mac OS X
• Linux, starting around version 2.1.60
• Microsoft Windows 2000/XP
• OpenBSD
• NetBSD
• Solaris Operating Environment

[edit] External links

• http://vtun.sourceforge.net/
• http://www.kernel.org/pub/linux/kernel/people/marcelo/linux-2.4/Documentation/networking/tuntap.txt